The present invention relates to a sliver guiding arrangement for drafting units of spinning machines, comprising at least two sliver guides which are assigned to adjacent slivers, are connected in front of a wedge-shaped gap of a clamping roller pair and are connected with one another to form a structural member by means of a coupling member which is driven via a driving device by means of a traversing rod to carry out traversing movements.
A sliver guiding arrangement is shown in German Patent Document DE-PS 907 274. In this arrangement, two adjacent sliver guides respectively are firmly connected with one another by a connecting strip. Two clamping springs originate from the connecting strip whose spring arms are constructed such that they clamp a drivable traversing rod of the spinning machine between one another. The connecting strip is therefore directly connected with the traversing rod. The individual sliver guides project into the wedge-shaped gap of a clamping roller pair which follows, without coming in contact with the individual rollers.
In drafting units with very high drafts, as they are required, for example, in ring spinning machines which spin drafting frame slivers fed in cans directly into yarns, it is necessary that the sliver guides be a defined distance from the clamping roller pair which follows. This distance is to be as independent as possible from possible tolerances of the traversing rod which extends through the whole machine.
An object of the present invention is to provide a sliver guiding arrangement having a traversing rod, in which the distance of the sliver guides to the clamping roller pair which follows is defined, and in which the position of the sliver guides can be determined in a precise manner independently of the traversing rod.
This and other objects are achieved by the present invention which provides that the driving device, which bridges a distance between the traversing rod and the coupling member, is arranged in the direction of the wedge-shaped gap in a movable manner relative to the coupling member, and in that the structural member is guided on a slideway in parallel to the wedge-shaped gap.
Because of the fact that a distance is provided between the traversing rod and the coupling member of the sliver guides which is bridged by a driving device which can be moved relative to the coupling member, differences in distance may be compensated. As a result of the fact the structural member is also guided in parallel to the wedge-shaped gap on a sliding surface, a defined distance exists between the sliver guides and the clamping roller pair which follows. Possibly, this defined distance may have a zero value.
The clamping of the slivers by the clamping roller pair does not impair the traversing of the slivers because the traversing takes place very slowly. It is sufficient, for example, to carry out a complete traversing movement only once an hour. Despite this very slow traversing movement, the coatings of the pressure rollers of the drafting units as well as the aprons of apron guides are sufficiently protected from premature wear.
In certain embodiments of the invention, the sliding surface is formed by a guide rail which is arranged at a distance from the clamping roller pair. Such a guide rail, which may be identical, for example, with the so-called reversing table of bottom aprons, can be aligned very precisely with respect to the wedge-shaped gap.
In other embodiments of the invention, the sliding surface may be formed by at least one roller of the clamping roller pair. This necessarily achieves the required precision of the distance of the sliver guides from the clamping roller pair.
In certain embodiments of the invention, the sliding surface is constructed as a stop against which the structural member will be placed. Regardless of whether this is a guide rail or a roller of the clamping roller pair, the stop permits a positioning of the structural member and thus of the sliver guides that is free of play at any time. By means of the transport of the slivers, the structural member pulls it itself against the stop.
When a roller of the clamping roller pair is used as the stop, as in certain embodiments, it is expedient for the coupling member to be provided with at least two spacing webs which are placed against the roller. As a result, the structural member is aligned very precisely with respect to the clamping roller pair without the requirement that the sliver guides themselves must pull completely into the wedge-shaped gap.
Advantageously, the driving device is arranged between two sliver guides and is non-slidably fastened to the traversing rod, in certain embodiments. For transmitting the traversing movements, the driving device expediently has lateral guides. These lateral guides may be arranged on a tongue-type bracket of the driving device, in which case the bracket engages in a recess of the coupling member. By means of these measures, it is ensured that the coupling member is arranged largely perpendicularly with respect to the traversing rod and in that, even in the case of slight deviation from the perpendicularity, the traversing movements are transmitted without any impairment of the parallelism of the coupling member with respect to the clamping roller pair.
In an advantageous embodiment, the driving device is constructed as a leaf spring. This has the additional advantage that the driving device can be placed on the guide rail with a slight contact pressure, whereby the level of the sliver guides with respect to the so-called drafting zone plane can be determined in a precise manner. In addition, if necessary, the leaf spring can apply the axial force in order to place the structural member against the stop.
In another embodiment of the invention, several coupling members are assigned to a single driving device. This results in a reduction of the manufacturing expenditures.
Furthermore, in certain embodiments, the driving device held on the traversing rod such that it can be folded away. In particular, it may be advantageous to fold all driving devices upward, for example, when the bottom cylinders of drafting units which extend through the machine are to be removed.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.